Impact resistant cambered lagging element

ABSTRACT

The present invention provides cambered impact resistant lagging roof panels for an arch support assembly which is designed for withstanding the effects of rock bursts in an underground mine. The impact resistant panels are aligned in a parallel series with their cambered faces facing upwardly and positioned transversely between adjacent sets of steel arch supports of the assembly. The impact resistant lagging panels are constructed as C-shaped metal channels with their channel openings facing downward. The panels are retained between adjacent beams under compression.

CROSS REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional Application No. 61/575,726, filed 26 Aug. 2011, the entire content of which is hereby incorporated by reference.

FIELD OF THE INVENTION

The present invention relates generally to mine roof control, and more particularly, it is directed to adding stability and maintaining the integrity of a steel support assembly or system designed for withstanding the effects of rock bursts during impact loading in an underground mine. Specifically, the invention pertains to lagging panels for roof control in such steel support assemblies or systems.

BACKGROUND OF THE INVENTION

As mining conditions continue to deteriorate due to depletion of easily accessible reserves, arch support installation is becoming more common. Currently all wide flange arch support assemblies are rigid. Cambered arch support assemblies are typically installed in an area where a roof fall has occurred and loose debris has been removed. In order to protect miners from secondary rock falls, arch support assemblies must be installed to protect the miners using the travel way. The object is for the cambered arch support system or assembly to absorb the impact of a rock burst impact load.

Typically, when an underground mine experiences a roof fall, the rock debris is removed from the area and the area of the roof fall is bolted and backfilled to reduce the risk of further rock fall. The process of bolting and backfilling the area of the roof that experience roof fall, however, is a time consuming process that requires the mine to stop production. In addition, backfill material is costly and backfilling the large roof fall area can become prohibitively expensive. Accordingly, steel arch support assemblies are more currently utilized as a simple and reliable system to protect personnel and moving vehicles from falling rocks.

Generally, these rigid arch support assemblies incorporate a roof structure spanning between adjacent arch supports of the assembly as lagging panels which are intended to absorb the impact loads from the falling rock. As an example, see the impact resistant lagging assembly disclosed in U.S. Patent Application Publication No. U.S. 2010/0266349, published on Oct. 21, 2010.

Presently, wide flange arch support assemblies deform when an impact load is applied and the arch sets comprising the assembly are compromised and cannot be preserved and therefore have to be replaced. Currently all lagging elements (roof impact yielding panels) used in these steel support systems have been designed using static load conditions without attention to dynamic impact loading. It is an object of the present invention to provide a lagging element which allows the steel support system to absorb and dissipate the impact energy from a mine roof fall.

The lagging elements currently used do not sustain impact loading adequately; particularly if more than one impact occurs. This usually results in a required replacement of the lagging elements or panels, which can create unsafe working conditions.

SUMMARY OF THE INVENTION

The impact resistant lagging panel system of the present invention is comprised of a parallel series of the elongate impact lagging panels which are cambered (curved) from end to end whereby the curvature of the panels protrudes or extends in the direction of perceived impact from rock bursts. The lagging panels are generally positioned transversely to and supported by and between cap beams of the arch support assembly. The lagging panels are preferably retained between the cap beams under compression and are also preferably constructed of metal C-shaped channels with their camber extending away from the channel opening.

The cambered lagging element of the present invention allows the steel support system to absorb and dissipate the impact energy from a mine roof fall. The cambered shape of the lagging element allows for a spring like resistance when impact loading is incurred. When the cambered lagging element of the present invention is subjected to impact, structural integrity is preserved.

The cambered lagging roof panel of the present invention is useful in areas where the immediate mine roof is unbolted or has the potential to become dislodged and fall on to the steel support system. The cambered lagging elements of the present invention are installed in the course (open area between steel support sets) to provide a means for the steel support system to dissipate the impact energy of falling rock from the mine roof.

BRIEF DESCRIPTION OF THE DRAWINGS

Other objects and advantages appear hereinafter in the following description and claims. The accompanying drawings show, for the purpose of exemplification, without limiting the scope of the present invention or the appended claims, certain practical embodiments of the present invention wherein:

FIG. 1 is an isometric view of the cambered impact resistant lagging panel of the present invention; and

FIG. 2 is an isometric view of an arch support assembly incorporating the cambered impact resistant lagging roof panels of the present invention, with portions of the roof panels sectioned away to expose the tie rods disposed thereunder.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

Referring to the drawings, the impact resistant lagging panels 10 are elongate elements cambered from end to end in or toward the direction of perceived impact. The panels 10 are preferably constructed of metal and provided with a C-shaped channel configuration with the camber extending away from the channel opening as illustrated.

The cambered lagging panels 10 are incorporated into the steel arch support assembly 11 shown in FIG. 2 as an aligned parallel series of adjacent roof panels supported by and between adjacent cambered cap beams 12. Tie rods 13 tie adjacent cap beams 12 together with the roof panels 10 thereby retained between the cap beams 12 under compression. Portions of the assembly of roof panels 10 is broken away in FIG. 2 to disclose tie rods 13. However, most of the tie rods 13 in FIG. 2 are not visible because they run under the C-shaped metal channels which form the lagging elements or panels 10.

The cap beams 12 have their opposite ends secured to upper ends of legs 14. The cap beams 10 and legs 14 are steel I-beams. The bottom ends of legs 14 are in turn secured to and supported on steel runner channels 15 which permits sliding of the entire arch support assembly 11 along a ground surface as a unit.

The curved lagging members or panels 10 are formed through conventional bending processes. The ends of the metal panels 10 are cut in a manner to allow maximum contact to the outer resisting surfaces, namely, the beam webs and flanges of the arch support set 16 being lagged. Once the arch support sets 16 are lagged 100%, the cambered lagging elements or panels 10 are pulled into compression via tie rods 13 between adjacent arch supports of sets 16, creating the resistance required to allow the panels 10 to function most effectively.

Once the panels 10 are pulled into compression using tie rods 13 this creates maximum resistance on both ends of the cambered lagging elements. This process allows any vertical loading incurred to be partially transitioned axially into the lagging panels 10, rather than strictly placing the panels 10 under bending stress.

The impact resistant lagging panels 10 are cambered or curved to allow spring-like resistance to dynamic loading. All vertical forces incurred are partially transitioned into an axial force, dampening bending stress effects. The enhanced integrity of the cambered lagging of panels 10 lengthens the life span of the panels 10 and the arch support set 16, minimizing replacement.

The lagging panels 10 are preferably constructed of steel. However, other suitable materials may be substituted. In addition, configurations other than the C-shaped channels may be utilized. 

1. An impact resistant lagging panel assembly comprising; spaced parallel beams; and a parallel series of elongate impact lagging panels cambered from end to end in the same direction of perceived impact and positioned transversely to said beams and supported by and between said beams.
 2. The assembly of claim 1, wherein said panels are retained between said beams under compression.
 3. The assembly of claim 1, wherein said panels are metal C-shaped channels with their camber extending away from the channel opening.
 4. The assembly of claim 3, wherein said panels are retained between said beams under compression.
 5. An arch support assembly for withstanding the effects of rock burst in an underground mine, comprising: an aligned series of spaced arch supports; and a parallel series of roof panels which are upwardly cambered between the ends thereof and transversely supported by and between said arch supports.
 6. The assembly of claim 4, wherein said panels are retained between said arch supports under compression.
 7. The assembly of claim 5, wherein said cambered metal roof panels are metal C-shaped channels with their channel openings facing downward.
 8. The assembly of claim 7, wherein said panels are retained between said arch supports under compression.
 9. An arch support assembly for withstanding the effects of rock burst in an underground mine, comprising; an aligned series of spaced arch supports, each support including a spaced pair of legs and an upwardly cambered cap beam having opposite ends thereof secured to upper ends of said legs; a parallel series of roof panels which are upwardly cambered between their ends and transversely supported by and between adjacent of said cap beams; and tie rods tying said adjacent cap beams together with said roof panels thereby retained between said cap beams under compression.
 10. The arch support assembly of claim 7, said cambered roof panels are metal and configured as downwardly open C-shaped channels. 